This invention relates to a rotary piston system, engine, or pump having a piston which moves inside a housing and in doing so enlarges and reduces an enclosed space. (Meyers Grosses Taschenlexikon, 5th Edition, 1995, Volume 19, page 7). A rolling piston engine with a discus-shaped plunger disk is disclosed in DE 588 285 C.
In this invention the term "rotation" is understood to mean that reciprocating oscillating movements are possible, i.e., that no complete rotations are performed in succession, but, for example, oscillating movements as well.
The rotary piston system described in what follows differs from state-of-the-art designs in its use of fewer parts (piston and rotary cylinder) and in its rotation about its center of mass (with no eccentricity). This results in high efficiency and permits simple and accordingly cost-effective designs. As is the case with other piston engines, it does so without valves.
Generally speaking, piston engines are based on the principle that a piston that is movable relative to a jacket increases or reduces an enclosed volume. The piston is assigned the function of restricting this volume as closely as possible. It can be shown that simple rotation of a piston about an axis results in rotation-symmetrical configurations and causes no changes in volume in any chambers present. An innovative step is represented by the Wankel engine, in which gearing causes oscillation of the piston in a special enveloping form to bring about change in volume in the chambers. The piston of the Wankel engine does not, however, rotate about the center of mass.